The present invention relates to a dosing device or mixing device for mixing, in a continuous process, a flowing primary liquid with one or more added secondary liquids for obtaining a flowing liquid mixture at a permanent, uniform mixing ratio of the mixed liquids. Especially, the processing industry and medicinal technology require access to dosing devices, by means of which two or more components in liquid state are continuously mixed with each other under conditions which yield uniform mixing ratios, i.e. uniform amounts of the components included, in a continuous mixing process. The device and the method according to the present invention are especially applicable in the cases where one or some components, so-called secondary components, are to be admixed to a flowing primary component and where the amount of secondary components in terms of volume is comparatively small or very small compared with the amount of the primary component in the finished mixture. In some cases, it is thus desirable to add enzymes, colorants, flavoring agents, vitamins etc. In a flowing quantity of liquid, the content of the added substances, the so-called secondary components, can be as low as 0.05-1% of the flowing primary component. It is possible by using the inventive method to obtain, with a uniform and continuous mixing ratio, a flow of liquid which can proceed to be packed with an equal content of additives in all packings. An example of such a process is, for instance, the preparation of lactose-free sterile milk, where the untreated sterilized and lactose-containing milk is continuously mixed with a quantity of sterile-filtered lactase before packing, the proportions of lactose-containing milk/lactase being in the order of 5-10,000, about the same mixing ratio being required in all packings that are continuously prepared. In some other cases, higher contents of secondary liquid are required as addition, for instance when colorants or flavoring foodstuffs.
Dosing equipment for mixing flows of liquid having different flow ratios is known, but such equipment has essentially been directed to obtaining a constant mixing ratio by letting the combined flows of liquid being joined and conducted in a loop, i.e. a certain part of the flow of liquid is deflected from the main conduit and recirculated to a point in the flow conduit which is positioned downstream. The mixed liquid or parts thereof will in this manner circulate several times through the loop to obtain a good mixing when the loop has finally been passed. The present invention, which operates without a mixing loop, is considerably simpler in its technical design and permits great flexibility as regards the amount and type of additives and is, above all, easier to adjust between the use of different mixing components. The dosing device according to the present invention preferably is adapted to be used in the foodstuff industry but may also be used in medicinal industry for continuous mixing of components in liquid state.